Book

Hi Tom,
Book is similar to other areas in Moodle like page or labels and without creating the full look as an entire image it is indeed limiting as you find.

To get more control of your visual layout you could import images into pages of your book, or abandon that approach and use pdf documents which can be sized and shaped to fit your designs and images will remain where you have placed them.

I sometimes export a presentation (ppt/keynote) as a series of images and put them in a lightbox gallery as it gives you the ability to rapidly flick around a presentation. If the presentation is set to be the size you want the images, then the exported images should by default be the size you want on screen.